Sweep plows are implements used for disrupting and destroying weeds growing in farm ground. Sweep plows are used in dryland soil common, for example, in areas of western Kansas, southwestern Nebraska and western Oklahoma. The advent of “ROUNDUP READY®” crops and the heavy use of herbicides such as ROUNDUP®, caused sweep plows to fall into disuse. However, in recent years ROUNDUP® resistant weeds have evolved which has revived the need for sweep plow implements.
Generally, a sweep plow implement includes a wheel-supported frame which is arranged to be pulled by a tractor. The frame of a sweep plow implement carries a pattern of sweep plow assemblies which include sweep plow blade assemblies and standards which rigidly mount the sweep plow blade assemblies to the frame. The elevation of the sweep plow blade assemblies is adjusted by adjusting the spacing between the wheels and the frame. Typically, during operation, the sweep plow blades are drafted through the soil just a few inches beneath the soil surface. The passage of the blade beneath the surface of the soil cuts and disrupts weed root systems. Other devices, such as “mulch treaders” mounted on the implement are also adapted to overturn the weeds so that the weeds do not reestablish. As sweep plow blades are drafted through the soil, considerable loads are transferred by the blades into the standards supporting the blade assemblies. Typically, each blade acts as an inverted foil which receives a downward force as well as significant drag. The resultant draft force may be envisioned as originating at the centroid of the sweep plow blade assembly and is directed rearward and down at about 30 degrees. A difficulty encountered with present sweep plow implements is that the draft forces acting on the sweep plow assemblies exert twisting moments on the frame structure. The resulting twisting of the frame causes the sweep plows to tilt downwardly and become misaligned. Another difficulty arises because the hydraulic cylinders which actuate the wheel assemblies and thereby control the elevation of the frame and sweep plow assemblies usually connect between the frame and an arm which extends up from a rockshaft which carries the wheel assemblies. When the wheels encounter a bump, the rockshaft acts as a torsional spring which allows the implement to bounce. Both the frame bending effect and the rockshaft torsion effect often forces an operator to increase the depth of the sweep plows to maintain the outboard tips of the sweep plow blades beneath the surface and to stabilize the implement from bouncing. This, in turn, causes the cutting action to be less precise and increases the power needed to draft the implement. Accordingly, what is needed is a sweep plow implement in which twisting moments on the frame and the bouncing action of the wheel assemblies are minimized so that sweep plow blade depth can be maintained with precision at a selected shallower depth.